Questions tagged [brown-dwarf]

Questions about sub-stellar objects that are like stars but never achieve permanent nuclear fusion because they are too low-mass.

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How large can a ball of water be without fusion starting?

How large can a ball of water be without fusion starting? Peculiar question: some explanation might be necessary. My young son is into ‘space’ and astronomy. One of his posters says that Saturn could ...
jdaw1's user avatar
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19 votes
2 answers
4k views

Can lightning occur in stars like the Sun?

In the Wikipedia article about lightining, the following explanation is given about the electrification process in clouds: The details of the charging process are still being studied by scientists, ...
ksousa's user avatar
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18 votes
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How can a brown dwarf be more massive than a star?

SDSS J0104+1535 is about 90 times more massive than Jupiter, making it the heaviest known brown dwarf. EBLM J0555-57Ab has a mass of about 85.2±4 Jupiter masses, or 0.081 Solar masses. I am confused. ...
Binita Rimal's user avatar
17 votes
1 answer
627 views

Is stellar ignition all-or-nothing?

The boundary between brown dwarfs and stars is around 80 Jupiter masses. Only stars generate a self-sustaining hydrogen fusion, although brown dwarfs sometimes fuse lithium and deuterium. Is hydrogen ...
Kevin Kostlan's user avatar
16 votes
1 answer
343 views

Do brown dwarfs have stripes?

Brown dwarfs (BD) are often depicted with stripes. brown dwarf Jupiter Pictures of BD resemble Jupiter but brown dwarfs ...
Heopps's user avatar
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14 votes
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What is going on with this (sub?) brown dwarf WISEPA J174124.26+255319.5?

In this Wikipedia article, it details about a T9 class brown dwarf named WISEPA J174124.26+255319.5. Apparently, this brown dwarf has 0.95 Jupiter masses, and 0.4 Jupiter radii (with rather low error)...
Max0815's user avatar
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13 votes
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Why can't our Sun be a binary with Jupiter as a T or Y dwarf?

I just learned about Brown Dwarfs, they are "failed" stars, they narrowly missed the stellar mass mark. I learned that Y Dwarfs have temperature as low as 80 Fahrenheit (The first one found by WISE ...
fahadash's user avatar
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13 votes
3 answers
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Are Brown and Sub-Brown Dwarfs secretly more common than stars?

I recently heard that Red Dwarfs are the most common type of star, and low-mass Red Dwarfs are the most common type of Red Dwarf. This seems to imply a generic trend that the lower the mass, the more ...
cowlinator's user avatar
13 votes
3 answers
691 views

Existence of planets larger than their host star?

The mass region of objects between ~ 0.5 Jupiter masses and 80 Jupiter masses (gas giants through to brown dwarfs and red dwarfs) is typified by an almost flat relationship with object diameter. There ...
Ingolifs's user avatar
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12 votes
1 answer
415 views

Is there a relation between mass, radius, and luminosity in deuterium-burning brown dwarfs?

I'm a worldbuilder and my setting has a lot of brown dwarfs. While I'm trying to keep my setting as science-compliant as possible, I can't seem to find any resources for brown dwarfs like there are ...
TerranAmbassador's user avatar
10 votes
2 answers
4k views

Why aren't brown dwarfs the dark matter?

There seems to be not enough matter to account for the fact that the speed of some stars located far from the Galaxy center is almost the same speed as those stars found nearer to the center of the ...
user6760's user avatar
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V471 Tauri's circumbinary brown dwarf non-observation; Applegate, or over-restrictive assumptions?

tl;dr Has the brown dwarf observation been disproven? I have just started reading about the interesting object V471 Tauri. The first two sentences of the introduction to The V471 Tauri System: A ...
uhoh's user avatar
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9 votes
1 answer
721 views

Why is detecting brown dwarfs difficult?

Why is detecting brown dwarf stars tedious and not always successful? They emit light in the infrared region, and given that we're surrounded by state-of-the-art technology in space today, why haven't ...
Pranay's user avatar
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8 votes
1 answer
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What is it like to see a brown dwarf turn into a star?

Brown dwarfs/failed stars can actually become stars, if they exceed a mass limit of about 80 Jupiter masses. This is when the internal pressure and temperature at the core become high enough to ...
Alastor's user avatar
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7 votes
2 answers
322 views

Can a brown dwarf accrete enough mass from red giant to become a star?

Let's assume a brown dwarf is on orbit around a main sequence star. Than the star becomes a red giant. Let's assume the brown dwarf has "the right" orbit and can syphon matter from the red ...
Heopps's user avatar
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7 votes
1 answer
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Mechanism for Brown Dwarf Fusion

I've read (at here, among other places) that during the Degenerate Era, star formation will end and the last stars will go out. But it was noted that there is still the possibility of star birth, ...
HDE 226868's user avatar
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7 votes
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Do brown dwarfs have starspots?

Do lithium-burning brown dwarfs (65+ Jupiter masses) have starspots too or do they occur only on hydrogen-burning stars?
John's user avatar
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7 votes
2 answers
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Can dark matter be normal matter after all? [duplicate]

MACHO's and RAMBO's are both baryonic (and leptonic) forms of matter that can't be observed by their nature. They barely emit or reflect light. Black holes, neutron stars, or brown dwarfs (or groups ...
Deschele Schilder's user avatar
6 votes
1 answer
699 views

Is the mechanism of solar flares on red dwarfs and brown dwarfs the same as that on the Sun?

The Sun has solar flares that are caused when there is a magnetic reconnection in the Sun's atmosphere, causing a loop of magnetic field to be ejected at high energy, along with a large number of ...
James K's user avatar
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Are brown dwarfs which don't sustain any fusion considered stars?

I was reading about the coolest stars, and was surprised to find about stars with a surface temperature lower than a candle, like 2MASS 0939-2448 A/B, of about 100 Celsius like CFBDSIR 1458+10B and ...
Pablo's user avatar
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5 votes
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Is there such a thing as a black dwarf

Does such a heavenly body exist called a black dwarf? It would be a Brown dwarf that has cooled to the point it no longer gives off heat or light.
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How do we know that 2MASS J0523-1403 is a red dwarf?

I was reading about red dwarfs, and stumbled upon this article about the least massive red dwarf, and noticed several peculiarities: The spectral type is L2.5 The luminosity class is V The mass is 67....
WarpPrime's user avatar
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5 votes
1 answer
182 views

Are we looking for brown dwarfs where the dark matter has to be?

We have been repeatedly assured that their ain't enough brown dwarfs to account for all the dark matter in our galaxy. My question is have we been looking in the right places? Or in more detail. ...
Blame's user avatar
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0 answers
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Why do degenerate objects get hotter as more mass is added?

After reading this question, I decided to post a question about degeneracy. I've seen simulations on large, $15\text{+ }M_J$ objects that are accreting mass. They do not grow in radius, instead they ...
slowerthanstopped's user avatar
4 votes
2 answers
261 views

If two binary brown dwarfs began to exchange gas with each other, would they both ignite into stars?

If two brown dwarfs got close enough to exchange gas with each other, could it trigger nuclear fusion within their cores? Is it possible for two brown dwarfs to orbit so closely and become a ...
Gliese's user avatar
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4 votes
1 answer
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Why is WISE J0521+1025's distance so uncertain?

If you look at the Wikipedia page List of nearest stars and brown dwarfs , you'll notice that all stars mentioned in the list have a very precise value; all are $\pm0.02$ ly (except for GJ 1005, but ...
WarpPrime's user avatar
  • 6,633
4 votes
2 answers
152 views

Do brown dwarf 'stars' fuse simple hydrogen (p-p reaction) at all?

I sometimes read that only deuterium-deuterium fusion can occur in brown dwarfs... And maybe deuterium-proton fusion? To He-3? In order to overcome Coulombic repulsion and, occasionally, fuse, protons ...
Kurt Hikes's user avatar
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4 votes
1 answer
247 views

Where are the two recently confirmed unusual brown dwarfs?

The News report of two confirmed unusual T-type brown dwarfs but they don't tell where in space or on the night sky they were found or how far they are from the Earth/Sun. The brown dwarfs are WISE ...
Ioannes's user avatar
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4 votes
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226 views

We are sure that there are no brown dwarfs closer than ______

I don't quite know how to word this question. How close could a brown dwarf be to us and have gone undetected until now? Or maybe, with what probability are we sure that there is no brown dwarf ...
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4 votes
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Brown dwarfs and planets

As far as I know, a brown dwarf is a 'star' whose core never underwent a fusion reaction, so it never became a star. So I was wondering if, apart from orbiting a star, is there any difference ...
stanley dodds's user avatar
4 votes
1 answer
205 views

Is it dangerous to look at an L-type brown dwarf from too close?

Are some L-type brown dwarves bright enough so that it would be dangerous to the eyes if one looked at them from habitable distance or closer? If not, are the weakest M-type stars undangerous to look ...
Giovanni's user avatar
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4 votes
1 answer
448 views

Very near GAIA DR2 sources - has Proxima Centauri been dethroned?

I made an extract of GAIA DR2 data for parallaxes greater than 500mas. Surprisingly I see a very significant number of sources with parallax greater that 1000, making them much closer than Proxima. ...
Ags1's user avatar
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4 votes
1 answer
75 views

At what point does an astronomical body's surface stop being gas giant-like and start being sun-like?

I've generally seen brown dwarfs depicted as more massive and slightly wider Jupiters in varying colors with banded cloud structures, sometimes hot enough to be visible glowing. I've also seen red ...
Adam Lincoln Steele's user avatar
4 votes
1 answer
144 views

Brown Dwarf Cloud Models

There has been research that suggests that the changing brightness of Brown Dwarves are due to bands of Iron/Silicate clouds. Several models have been made that supports that hypothesis. My question ...
Hippeus_Lancer's user avatar
3 votes
1 answer
1k views

What is the closest heavenly body to our solar system

What is currently the closest known heavenly body, brown dwarf, rogue planet or other to our solar system? At one time it was Alpha Centauri.
P Pitch's user avatar
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3 votes
3 answers
760 views

How do we calculate heat flow or cooling rate for no fusion brown dwarf star?

I was reading this article and it said something that didn't sit right with me. "SIMP0136 still gives off light mostly in the infrared wavelengths, as its temperature is now approximately 830° C (1,...
0tyranny0poverty's user avatar
3 votes
1 answer
936 views

Using the "Lithium test" to distinguish low-mass stars and brown dwarfs

Both low-mass PMS (pre-main-sequence) stars and young brown dwarfs can fuse lithium in their cores and the lithium can be depleted throughout the star/brown dwarf very quickly. Wiki. Then the Li I ...
questionhang's user avatar
  • 3,103
3 votes
1 answer
413 views

"Turn on point" for fusion?

I've read that when a body reaches about 13 times the mass of Jupiter that deuterium fusion starts and the body becomes a brown dwarf instead of a planet. I have a multiple question. Are there any ...
Jack R. Woods's user avatar
3 votes
1 answer
576 views

Jupiter vs brown dwarf star

What would happen to Jupiter if a brown dwarf star collided with it, and vice versa what would happen to the brown dwarf star?
David Jones's user avatar
3 votes
1 answer
183 views

Brown dwarf magnetic activity

I have not been able to find an answer to my question through google, and therefore ask it on this medium. Do brown dwarfs have spots and faculae similar to other heavier stars?
user4437416's user avatar
3 votes
2 answers
95 views

How would we tell the difference between low mass objects that formed by direct collapse or in an accretion disk?

In this question about rogue planet/sub brown detection there are a couple of comments about classification of non-stellar, low mass, free floating objects. Part of one of the answers is - Some "...
Futoque's user avatar
  • 133
2 votes
2 answers
848 views

How do I understand a brown dwarf with a M-type spectrum?

There are a large fraction of M dwarfs which are claimed to be brown dwarfs. Why do we still use M-type and not create a new stellar type like L, T and Y? The main signature of M is TiO absorption ...
questionhang's user avatar
  • 3,103
2 votes
2 answers
404 views

Can a high enough density ignite a gas giant into a brown dwarf?

I wonder whether the nuclear fusion of brown dwarfs and more massive stars really depends on their mass only or if it could also start nuclear fusion if it is dense enough but not as massive as brown ...
Ioannes's user avatar
  • 1,090
2 votes
1 answer
88 views

Life around a former brown dwarf

Imagine a brown dwarf of any given mass (between the usual 13j - ~90j mark). It orbits within the outer edge of a reasonably quiet star's habitable zone. Within about 55 million years, it stops fusing ...
Kazon's user avatar
  • 587
2 votes
1 answer
241 views

Would dropping a white dwarf or a "still-hot" stellar core into a large planet or brown dwarf create a star?

In the Wikipedia article about stellar engineering, I found this quote: In The Saga of the Seven Suns, by Kevin J. Anderson, humans are able to convert gas giant planets into stars through the use of ...
WarpPrime's user avatar
  • 6,633
2 votes
1 answer
297 views

Why have brown dwarf classes been dubbed L, T and Y?

The classes used to categorize stars (O, B, A, F, G, K, M) are in a bizarre order for historical reasons. Stars were labeled based on the spectral lines that were visible, then the categories were put ...
usernumber's user avatar
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2 votes
1 answer
119 views

Is there a luminosity class for brown dwarfs?

I've been reading about brown dwarfs, and checking their spectral types, and I noticed that they do not have a luminosity class (V, VI, etc). So I am wondering, do brown dwarfs have a luminosity class,...
WarpPrime's user avatar
  • 6,633
2 votes
2 answers
659 views

How close to a brown dwarf would a planet need to be to receive as much light as Earth?

How close to a brown dwarf would an orbiting planet need to be in order to receive as much sunlight as Earth receives from the Sun?
Quadratic Wizard's user avatar
2 votes
1 answer
81 views

Sub brown dwarf cores

I’ve heard that the cores of sub-brown dwarfs (sub brown dwarfs mass objects that form the same way as stars and brown stars instead of forming like planets do.) are different from that of gas giants. ...
blademan9999's user avatar
2 votes
1 answer
161 views

Brown Dwarf Sun: How dim can a star be in the visible spectrum and still provide enough heat for a planet to be habitable?

After reading this question on wordbuilding. I saw that a brown dwarf emits most of its energy in the infrared which made me wonder: How bright would such a star appear from it's exoplanet in the ...
SurpriseDog's user avatar